There is a great desire to find alternative methods of energy production. To this end, technologies like fuel cells, which rely on electro-oxidation of various catalysts are becoming increasingly popular. A growing area of interest is the area of biological fuel cells which use enzymatically oxidized biocatalysts for energy production.
Gas-diffusion electrodes (GDEs) have been widely used in alkaline and phosphoric acid fuel cells and in metal-air batteries where they are used to incorporate metal (Pt, Pd, Ag) or metal oxide (MnO2, Co2O3) catalysts that are supported on dispersed carbonaceous materials (usually activated carbon or carbon blacks.) However, GDEs have been poorly explored for bio-catalytic systems, such as oxygen reduction catalyzed by multi-copper oxidases (MCO) due to the challenge of providing materials where the functional material: is electrically conductive with non-compromised electron conductivity; is hydrophilic enough to allow immobilization of the enzyme from an aqueous solution; has a functionalized surface (either naturally or is susceptible to synthetic functionalization strategies) to allow fortuitist enzyme-support interaction or chemical immobilization; and is susceptible to hydrophobization, either by chemical modification or by blending with a hydrophobic composite or dispersed phase (such as PTFE or PTFE-modified carbon black) to yield an effective transition to super-hydrophobicity, as required in the GDL.
Accordingly there is a need for novel biocathodes for biofuel cells that satisfy the above-identified conditions.